Solvents Drying and Drying Agents. - 50megs

Solvents Drying and Drying Agents Properties of solvents and methods used for drying them with specific drying agents

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Removing water from Solvents There are various ways of removing water and other impurities from a solution. This can become a major task once the used reagents are also sensitive towards water e.g. Grignard reagents or enolates. If water is one of the products, it also has a detrimental effect on the yield and/or reaction rate. In those cases, drying agents like activated alumina¹, calcium hydride (CaH2 ), sodium metal (in combination with benzophenone which forms a dark blue ketyl radical), lithium aluminum hydride (LiAlH4 ) or phosphorous pentoxide (P 4 O10 ) are used to chemically destroy the water. The drying agents commonly used in the organic laboratories are the anhydrous forms of calcium chloride (CaCl2 ), sodium sulfate (Na2 SO4 ) Calcium sulfate (CaSO4 (as Drierite) and magnesium sulfate (MgSO4 ). Organic liquids are considered to be wet if they contain water,but the organic liquid will still be a liquid after it is dried.

Activated Alumina Activated alumina ¹ is a very porous form of aluminum oxide of high surface area which adsorbs liquids and gases without any change in form. Activated alumina will not soften or disintegrate when immersed in liquids. Activated alumina may be regenerated to its original adsorption efficiency by heating to a temperature between (177-316°C). Activated alumina can be used for: Reconditioning of mineral oils like transformer or insulating oils. Removal of oil vapor mist from compressed air. Drying of organic liquids to a moisture level of 10 ppm or below. Drying of various liquids such as Benzene, Carbon, Tetrachloride, Chlorobenzene, Ethyl Acetate, Transformer oil, Vegetable oils etc.

Solvents drying guide

TO DRY

USE ONE OF THE FOLLOWING DRYING AGENTS

Alcohols

Anhydrous forms of potassium carbonate; anhydrous magnesium or calcium sulphate; quicklime.

Alkyl halides Aryl halides

Anhydrous calcium chloride; anhydrous forms of sodium sulphate, magnesium sulphate, or calcium sulphate; sodium pentoxide.

Saturated and Aromatic hydrocarbons

Anhydrous calcium chloride or sulphate; metallic sodium; phosphorus pentoxide.

Aldehydes

Anhydrous sodium sulphate; anhydrous magnesium or calcium sulphate.

Ketones

Anhydrous sodium sulphate; anhydrous magnesium or calcium sulphate; anhydrous potassium carbonate.

Organic bases (amines)

Solid potassium or sodium hydroxide; quicklime; barium oxide.

Organic acids

Anhydrous sodium sulphate; anhydrous magnesium or calcium sulphate.

Solvents: Properties and Drying agents Boiling Flash Pt. Density Pt. °C °C

Solvent

Drying agent

Acetone

56

0.791

-18

K 2 CO3 ; Molecular sieve 0.3nm; CaCl2

Acetic acid

118

1.049

+40

P 2 O5 ; CuSO4

Acetic anhydride

136

1.082

+49

CaCl2

Acetonitrile

82

0.782

+6

CaCl2 ; P 2 O5 ; K 2 CO3 ; calcium hydride; Molecular sieve 0.3nm

Aniline

184

1.022

+76

KOH; BaO

Anisole

154

0.995

+51

CaCl2 ; Na; distillation

Benzene

80

0.879

-10

CaCl2 ; distillation; Na; Pb/Na; ; calcium hydride; Na wire; Molecular sieve 0.4nm

1-Butanol

117

0.810

+29

K 2 CO3 ; distillation

2-Butanol

100

0.808

+24

K 2 CO3 ; distillation

tert-Butanol

82

0.882

+11

CaO; Freezing

n-Butyl acetate

127

0.882

+33

MgSO4 ;

Carbon disulphide

46

1.263

-30

CaCl2 P 2 O5 ;

Carbon tetrachloride

77

1.594

none

distillation; P 2 O3 ; Pb/Na; Molecular sieve 0.4nm

Chlorobenzene

132

1.106

+29

CaCl2 ; distillation;P 2 O5

Chloroform

62

1.486

none

CaCl2 ; P 2 O5 ; Pb/Na; Molecular sieve 0.4nm

Cyclohexane

81

0.799

none

Na; Na/Pb; LiAlH4 ; Molecular sieve 0.4nm

Cyclohexanone

155

na

na

Distillation

Decahydronaphthalene ~190 (Dekalin)

0.886

<54

CaCl2 ; Na; Pb/Na

Dichloromethane

40

1.325

none

CaCl2 ; Pb/Na; calcium hydride; Molecular sieve 0.4nm

Dicyclopentadiene: (cyclopentadiene dimer)

170

na

na

Refractionation: distillate at 40 - 42°C. (Use at once! or keep in dry ice/acetone bath no longer than 1 Hr.)

Diethyl carbonate

126

0.975

+25

Na2 SO4 ; K 2 CO3

Diethylene glycoldibutyl ether

225

0.885

+118

CaCl2 ; Na

Diethylene glycol dimethyl ether

155 165

0.906

+70

CaCl2 ; Na

Diethyl ether

34

0.714

-40

CaCl2 ; Na; Pb/Na; LiAlH4 ; Na wire/benzophenone; Molecular sieve 0.4nm

Di-isopropyl ether

68

0.726

-23

CaCl2 ; Na; Molecular sieve 0.4nm

Dimethyl formamide

153

0.950

+62

distillation; Molecular sieve 0.4nm

Dimethyl sulfoxide

189

1.101

+95

distillation; Molecular sieve 0.4nm

1,4 Dioxane

101

1.034

+11.8 CaCl2 ; Na; Molecular sieve 0.4nm

Ethanol

79

0.791

+12

CaO; Mg; MgO; Molecular sieve 0.3nm

Ethyl acetate

77

0.901

-4

K 2 CO3 ; P 2 O5 ; Na2 SO4 ; calcium hydride; Molecular sieve 0.4nm

Ethylenediamine: (1-2 diaminoethane)

118

na

na

Simple distillation.

Ethylene glycol

197

1.109

+111

distillation; Na2 SO4

Ethylene glycol monoethyl ether

135

0.930

+41

distillation

Ethylene glycol monomethyl ether

125

0.965

+52

distillation

Ethyl formate

54

0.924

-20

MgSO4; Na 2SO4;

Formamide

211

1.134

155

Na2 SO4 ; CaO

Glycerol

290

1.260

+176

distillation

Heptane

98

0.684

-4

calcium hydride; Na wire

n-Hexane

69

0.659

-23

Na; Pb/Na; LiAlH4 ; calcium hydride; Na wire/benzophenone; Molecular sieve 0.4nm

Isobutanol

108

0.803

+28

K 2 CO3 ; CaO; Mg;

Isobutyl methyl ketone 117

0.801

+15.5K 2 CO3 ; 4

Methanol

65

0.792

+11

Mg; CaO; Molecular sieve 0.3nm

Methyl acetate

57

0.933

-10

K 2 CO3 ; CaO;

1-Methyl-2-pyrrolidone 202

1.026

+95

Na2 SO4 ; distillation; Molecular sieve 0.4nm

Methyl Ethyl ketone

80

0.806

-44

K 2 CO3 ;

Nitrobenzene

211

1.204

+92

CaCl2 ; P 2 O5 ; distillation;

n-Pentane

36

0.626

-49

Na; Pb/Na;calcium hydride; Na wire

Pet ether

mixture na

na

calcium hydride; Na wire/benzophenone; Molecular sieve type 4A

1- Propanol

97

0.804

+15

CaO; Mg

2-Propanol

82

0.785

+12

CaO; Mg; Molecular sieve 0.3nm

Pyridine

116

0.982

+20

KOH; BaO; Molecular sieve 0.4nm

Tetrahydrofuran

66

0.887

-17.5

Molecular sieve 0.4nm

Tetrahydronaphthalene 208 (Tetralin)

0.973



CaCl2 ; Na

Thionyl chloride

48

na

na

Redistill.

Toluene

111

0.867

+4

distillation; Ca; CaCl2 ; Na; Molecular sieve 0.4nm

Trichloroethylene

87

1.462

none

distillation; Na2 SO4 ; K 2 CO3

Xylene

137/140 -0.86

+25

distillation; Na; CaCl2 ; Molecular sieve 0.4nm

Reference: http://www.deltaadsorbents.com/activated_alumina_2.php delloyd.50megs.com

Signature: Dhanlal De Lloyd, Chem. Dept, The University of The West Indies, St. Augustine campus The Republic of Trinidad and Tobago. Copyright: delloyd2000© All rights reserved.